Blades of various types are known for different applications. For example, in the field of hobby and crafts, it is known to use fine edged blades for cutting and shaping of hard materials such as wood, cardboard, Bristol Board, and other similar such materials according to the desired patterns.
Similarly, the use of metal scalpels in surgery is well known. Till the early part of the 20th century, such scalpels comprised of single piece metal surgical knives which required repeated sharpening to ensure reuse.
Around 1915 a system of a disposable blade which could be fitted on a metal handle was created in the USA. This system, the fitment dimensions of which were harmonised internationally in 1985 by the International Standards Organisation (Standard No. ISO 7740: 1985—Instruments for Surgery—Scalpels with detachable blades—Fitting dimensions) is the system which is currently used worldwide. However, this system has several design weaknesses, which puts both the user and the patient at risk. The risks arise due to:    1. Difficulty in fitting and removal of the blade on the handle. As a result, nursing and surgical personnel who use the scalpel are at a risk of injury even when they have been trained in methods of fitting and removal of blades on the handle.    2. Another problem associated with such designs is that the risk of accidental injury by a blood-contaminated blade is high when removing the blade. This is because it is necessary to use a finger to lift the heel of the blade thereby bringing the fingers close to the cutting edge of the blade.    3. A third problem is that fitting and removal of blades is often hampered by inaccurate fitment dimensions.    4. Blades are known to break during fitting on and removing from the handle.    5. Blades often will break during use on a patient, especially in arthroscopy procedures, where the blade encounters hard tissue or bone.
Scalpels have also been used by hobby enthusiasts as well as in industry for various purposes. For example, it is common for hobbyists to use scalpels to devise models using wood. It is also known to use such scalpels in industry to ensure delicate cuts in material such as polymeric material. However, industrial users or hobbyists often are not trained in the techniques of fitting and removing blades from handles and therefore run the risk of being cut during use. Another problem faced in industrial or hobby applications is that the blade is subjected to heavy lateral forces as blades are also used for scraping, whittling and chiseling. Blades will therefore frequently break thereby increasing the chance of injury.
Blades with a reinforced back in the form of a rib are available which are stronger but which are nevertheless known to break during use or during transportation. These blades are up to four times more expensive than standard surgical blades.
During the 1970's disposable scalpels were introduced in the market. Though their introduction eliminated the risk associated with fitting on and removing blades from handles they were not widely accepted, especially by surgeons, due to the lack of weight and feel of the disposable scalpel compared to the traditional metal handle. A second strong disincentive is the high cost of disposable scalpels. In many countries disposable scalpels are not in use.
More recently “blade remover units” have been introduced but are expensive. Such blade removal units are also not an integral part of the design of a scalpel, which is considered necessary for a device to be rendered safe. Their usage also means one more device being introduced into the sterile field (they are non-sterile) and does not eliminate the need for a sharps disposal container. In many countries “blade remover unit” are not in use.
In recent years, due to OSHA, USA regulations a proliferation of safety scalpels have been introduced into the market. The very first devices that were introduced were essentially disposable scalpels with engineered safety features. Again these were not widely accepted, despite the pressure of the regulations, for the very same reasons i.e. lack of weight and feel of a traditional scalpel metal handle, high cost of each device, unfamiliarity with features, and the training required to use them.
Another important feature in surgery over the past few years has been concern over the possibility of infection in operating personnel from patients suffering from highly contagious diseases such as AIDS, hepatitis, or other related contagious diseases. It is therefore important to be able to either provide disposable scalpels or provide for handles where the blade can be easily disassembled after use and the scalpel handle cleaned thereafter.
A second generation of safety scalpels, recognising the importance of the weight of a traditional scalpel metal handle, have either added weight to their plastic safety scalpels or have introduced a metal handle with proprietary system of fitment. To these handles only a blade cartridge with proprietary fitment system can be fitted. Surgical Blades with the internationally accepted and used ISO 7740: 1985 system cannot be fitted on these handles. Though these handles may have the weight, comparable to a traditional metal handle, they do not have the feel of reusable one due to their bulk or sliding sheaths etc. These are also the most expensive scalpels available in the market.